Sylvania



110 Drawing.

UNITED STATES PATENT OFFICE.

FRANK G. BREYEB, ALBERT E. HALL, AN'D GEORGE B. WALTZ, 0F PALMERTON, PENN- SYLVANIA, ASSIGNORS TO THE NEW JERSEY ZINC COMPANY, OF NEW YORK, N. Y.,

A CORPORATION OF NEW JERSEY.

PRODUCTION OF METAL OXIDS AN D OTHER COMPOUNDS 0]? METALS.

To all whom it may concern Be it known that we, FRANK G. BREYER, ALBERT E. HALL, and GEORGE R. WALTZ, all citizens of the United States, residing at Palmerton, Pennsylvania, have invented certain new and useful Improvements in the Production of Metal Oxids and other Compounds of Metals; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which ita pertains to make and use the same.

T is invention relates to the production of metal oxids or other compounds of metals volatilized by the WVetherill process.

Metallic oxids, such, for example, as zinc oxid and leaded zinc oxid, as well as other compounds of metals volatilized by the Wetherill process, such, for example, as basic lead sulfate or sublimed lead, have heretofore been more or less extensively produced by the so-called \Vetherill process. In speaking of metals volatilized by the \Vetherill process, we intend to describe and cover such metals as are volatilizable at the temperatures attainable in the \Vetherill' process, and for the sake of brevity, we shall hereinafter designate these metals as volatilizable metals. In the case of certain of such metals, the final or desired compound or compounds thereof are the result of a sequence of actions in which the metalliferous materials of the charge are reduced, the reduced metal volatilized and then oxidized or otherwise compounded, while in other cases a metal compound may be directly volatilized, with or without subsequent oxidation or compounding.

By the expression \Vetheril] process as we have used the same herein is to be understood the furnacing step of the process for producing metal oxids or other compounds of volatilizable metals in which acharge of the metalliferous materlal mixed with a reducing agent and spread on an ignited bed of fuel is subjected to a combustion supporting blast oi draft and brought to a sufficiently high temperature to reduce the metalliferous materials and volatilize the reduced metal or metals (and (or) to volatilize a metal or a metal compound or compounds) without bringing the charge to a condition where it becomes rmpervious to the blast or draft, the entire charge being supported on a furnace hearth Specification of Letters Patent.

Application filed July 12, 1919. Serial No. 310,440.

Patented Nov. 18, 1919.

or grate designed to hold it without letting any considerable part drop through, and the worked-off material being discharged as a clinker or sinter. The furnacing step is independent of the subsequent treatment of the laden furnace gases and of the collection of the metal compound or compounds.

As a typical example of the VVetherill process, as heretofore usually practised, we will briefly describe the customary procedure in the commercial production of zinc oxid, including leaded zinc oxid. The furnacing step is generally carried out in a furnace having a broad expanse of horizontal grate or hearth roofed over with an arch, and associated with appropriate instrumentalities for permitting the passage there through and into the charge, by either a blast or draft, of a combustion supporting gas. It is customary to first charge upon the furnace grate or hearth a layer of buckwheat anthracite coal (which is thereupon ignited, usually by the residual heat of the furnace) and by means of a forced blast or draft of air to bring this initial layer of coal to well-developed combustion. Upon this layer of bed coal is then charged the customary mixture or working charge characteristic of the 'etherill process, that is to say, a mixture of finely divided reducing coal with the finely divided zinciferous (or zinciferous and plumbiferous) material, such as zine silicate, roasted zinc blends, roasted so-called mixed sulfids of zinc and lead, spelter retort residues, or other reducible zinc-containing or zinc-andlead containing material at the disposal of the operator. The forced air draft is continued, and, when the familiar flames of greenish tint, known as zinc candles, begin to make their appearance above the upper surface of the charge, indicating that the reduction and volatilization of the zinc and its oxidation to the form of fume is well under way, the products of combustion carrying the zinc oxid fume and other volatilized metallic compounds are conveyed through the customary cooling fines, etc., to the bag-room wherein, in a cooled condition, they filter through the bags and pass oif into the atmosphere, leaving the fume collected in the interior of the bags, from which it is removed at convenient intervals. The furnace operation is continued until the production of fume therefrom in appreciable quantitv ceases, whereupon the residual charge, which is, to a large extent, sintered together, is broken up by long-handled rabbles and pried up and lifted or scraped out through the furnace doors into a receiving pit, or the like, preparatory to the starting of a new operation. The coal or other carbonaceous material of the charge serves the two-fold purpose of furnishing a reducing agent for effecting the reduction of the metalliferous materials of the charge and of furnishing, by combustion, the necessary degree of heat to bring these materials to the reducing temperature characteristic of the process.

As thus ordinarily practised, the abovedescribed furnace operation is attended with certain defects interfering with its full efficiency. Prominent among these defects is the inevitable tendency to the formation of blow-holes or craters at various regions of the charge. lVorking or rabbling of the charge to break up these blow-holes involves considerable labor, and, in addition, the formation of blow-holes causes waste of fuel and inefliciency in the recovery of values. A further defect of the above-described furnace operation is that the forced draft tends to project into the free space above the charge more or less dust, and thus dusting is further aggravated by the rabbling operations. This dust contaminates the fume and damages its color and marketability. These and many of the other defects of the above-described furnace operation as heretofore generally practised are overcome to a very remarkable extent by modifying the heretofore customary practice in accordance with the improvements described in the application for Letters Patent of the United States of Frank G. Breyer, James A. Singmaster and Albert E. Hall, Serial No. 270,179, filed January 8, 1919. These improvements consist in supplying either or both the bed fuel and the working) charge to the furnace hearth in the form of riquets. The improved results attendant upon this modification in the prior customary practice are described in detail in the aforementioned application.

We have discovered that a further decided improvement in the efficiency of the aforementioned furnace operation can be secured by appropriately modifying the relative proportions of fuel, including reducing agent. in the working charge and bed fuel in accordance with the principles hereinafter explained. Thus, briefly, we have discovered that when the greater proportion of the total fuel of the charge is placed in the form of briquets in the bed fuel, rather than in the working charge as has heretofore been customary, a very complete working-ofi' of the volatilizable metal values is effected, The relatively deep bed of fuel briquets when in full combustion imparts to the superposed working charge a hi hly reducing atmosphere and a sufficient y hi h and very uniform temperature where y 90% or more of the volatilizable metals may be recovered from the metalliferous material of the charge, as compared with recoveries of about under the heretofore customary furnace practice with unbriqueted charges and recoveries of from 80 to 85% with briqueted charges as described in the aforementioned Breyer-Singmaster-Hall application.

The residual charge from the hereinbefore described furnace operation (with unbriqueted charges) consists of a more or less sintered mass containing the ash of the consumed fuel, unconsumed fuel and the worked-off metalliferous material. These various materials are more or less mixed together and their mixed condition seriously prejudices subsequent treatment of the residue and the separation and recovery there from of such valuable materials as it usually contains. When this heretofore customary practice is modified by supplying the usual working charge mixture to the furnace hearth in the form of briquets, the workedoff charge is still a mixture of ash, unconsumed fuel and worked-ofl' metalliferous material. By plaein the greater proportion of the total fue of the charge in the bed fuel in the form of briquets, and by supplying the working charge, with its correspondingly reduced content of fuel and reducing agent, in the form of briquets, we very materially reduce the amount of combustible material associated with the metalliferous material of the working charge and thereby enable the working charge briquets to retain for the most part their original form and shape, whereby the Worked-off ore or metalliferous bri uets may be readily separated from the clinkered residue of the bed fuel briquets. At the same time, the amount of ash associated with the worked off ore briquets is of such small amount that these worked-off briquets can be subsequently treated for the recovery of further metallic values without serious difficulty.

In the customary commercial practice of the \Vetherill process, the total carbonaceous material in the entire charge, including the bed fuel and the Working charge mixture, is several times greater than the theoretical amount required to reduce the compounds of a the volatilizable metals in the charge. It has heretofore been the general practice to place the greater proportion of the total carbonaceous material of the entire charge in the working charge mixture. For. example. when operating with the well known Franklin furnace zinc oxid ores. it is customary to place from about fifteen (15) to twenty-five (25) per cent. of

the total carbonaceous material of the entire charge in the bed fuel, while the remaining eighty-five (85) to seventy-five (75) per cent. of the total carbonaceous material is mixed with the ore to form the Working charge. In general terms, the layer of bed fuel is approximately one inch in depth of thickness, while the working charge mixture is spread over the ignited bed fuel in a layer from about five (5) to seven (7) inches in depth or thickness.

\Ve have discovered that a very considerable proportion of the carbonaceous or other combustible material can be withdrawn from the working charge and placed in the bed fuel when the bed fuel is supplied to the fur nace hearth in the form of briquets. Thus, for example, when operating with Franklin furnace zinc oxid ores, we have obtained excellent results by placing from about seventy-five (75) to eighty-five (85) per cent. of the total carbonaceous material of the entire charge in the bed fuel and supplying this bed fuel to the furnace hearth in the form of briquets. The remaining twenty-five (25) to fifteen (15) per cent. of the total carbonaceous material is then admixed with the ore to form the workin charge. The working charge is also pre erably briqueted and spread on the ignited bed fuel briquets.

In carrying out the invention, the briqueted bed fuel is charged onto the furnace hearth in any appropriate manner, ignited and brought to full combustion by passing a combustion-supporting gas, such as air, into the bed fuel briquets. The working charge is then spread onto the ignited bed of fuel briquets, and the resulting efliuent is withdrawn from the furnace and appropriately treated for the removal and collection of the metallic compounds contained therein. In working with Franklin furnace zinc oxid ores, we have secured very satisfactory results by charging the briqueted bed fuel in a layer of approximately five (5) to six (6) inches in depth or thickness, and spreading onto the ignited layer of these bed fuel briquets a layer of workin charge briquets of approximately four (4 to five (5) inches in depth or thickness.

\Vhen the compounds of the volatilizable metals of the working charge have been worked-off to the desired extent. the residual charge may be withdrawn or discharged from the furnace in any suitable manner. This residual charge consists of a relatively thin layer of clinker on which rests the worked-off ore briquets. During the process the bed fuel briquets undergo substantially f complete combustion, and are discharged as a clinkered ash. On the other hand, the physical form of the briqueted working charge is not materially altered and for the most part the worked-oil ore briquets retain their original shape with only incipient fusion.

The bed fuel briquets may be prepared by compressing finely divided coal, together with a suitable binder, such, for example, as the concentrated waste sulfite liquor of the sulfite paper pulp industry. Various forms and grades of carbonaceous material are available for the bed fuel briquets. Thus, for example, anthracite coal below the No. 3 buckwheat size, such as No. 4 buckwheat, colliery washings, dirt ooal, dust coal, as well as coke breeze, may be utilized in the production of the bed fuel briquets. The bed fuel briquets are of such size and shape as to materially reduce the resistance to the combustion supporting gas, and nevertheless to supply such a substantially uniform substratum for the support of the superposed working charge as to give free access therethrough and practice. ly equal distribution thereto of the combustion supporting gas. To this end, the bed fuel briquets, as well as the working charge briquets, should be of substantially uniform size, and preferably of such shape that they roll or tumble easily over one another. Thus, we have found the so-called pillow block, eggette, rounded pillow block, over-stuffed illow, and simllar shapes well suited to t e purposes of the invention.

While the working charge consisting of a mixture of the metalliferous material and an appropriate reducing agent maybe supplied to the ignited la 'er of bed fuel briquets in an unbriqueted orm, we prefer to briquet the working charge because of the many attendant advantages. Furthermore, we wish it to be understood that the metalliferous material may be briqueted alone, without briqueting the reducing agent, or the reducing agent may be briqueted alone without briqueting the metalliferous material, or the reducing agent and the metalliferous material may be separately briqueted. However, our preferred practice is to briquet a mixture of the metalliferous material and the reducing agent.

The reducing agent of the working charge may be of any suitable kind, and while we. now prefer to employ carbonaceous material as the reducing agent, it will be understood by those skilled in the art that reducing agents other than carbonaceous materials are available for the purpose of the invention. One of the advantages of employing a briqueted reducing agent in any of the forms hereinbefore described is that it permits the use of carbonaceous materials of cheaper grades and finer mesh, such as anthracite coal of finer mesh than No. 3 buckwheat, colliery washings, dust coal, coke breeze and the like.

The bed fuel briquets and the working charge briquets may be prepared in any suitable binder, such as concentrated waste sulfite liquor of 30 Baum, moldin the mixture into briquets of the desire size and shape, and drying or baking the briquets at a temperature of approximately 200 C., so as to impart to them the desirable amount of resistance to crumbling and breaking so that they may be freely subjected to the rough handling incident to storing them, conveying them to the fur nace, and incident to char ing them into the furnace either by han or otherwise. In the case of the briqueted metalliferous material, it is also desirable that the briquets possess such resistance to crumbling and breakin as to substantially maintain their form uring the entire furnacing operation, so that they are for the greater part discharged from the furnace in substantially their original physical form.

When practising the Wetherill process in accordance with the principles of our present invention, the residual charge consists of a more or less clinkered coal ash, resulting from the combustion of the bed fuel briquets, and a residue, resulting from the workingoif of the metalliferous charge. When, as 1n the preferred embodiment of the invention, the metalliferous material of the working charge is supplied to the furnace hearth in the form of briquets, this residue contains the worked-off ore briquets in substantially their original physical form. Some of the working charge briquets will almost inevitably become broken or crushed in the preliminary handling and furnacing operation, but these briquets for the greater part retain their original physical form. After the furnacing operation, these briquets are remarkably hard and almost coke-like in their physical characteristics, and are readily separated from the clinkered coal ash of the bed fuel briquets.

This ca ability of readily separating the worked-o metalliferous or ore briquets from the ash of the fuel briquets is of especial advantage when the worked-oil ore briquets are to be subjected to further treatment for the recovery of valuable metals not volatilizable by the lVetherill process. As a result of practising the \Vetherill process in accordance with our present invention, this advantage is greatly augmented by the fact that the worked-off metalliferous briquets contain at most only a relatively small amount of ash. \Vhere the working charge briquets consist of a mixture of metalliferous material and carbonaceous reducing agent, the worked-oft" briquets will contain, in addition to the worked-ofl metalliferous material, the ash from the consumed carbonaceous reducing agent as well as the unconsumed portion of the reducing agent. The ash is composed principally of silica and alumina, and is generally objectionable in any subsequent treatment of the worked-off metalliferous briquets. Thus, for example, in those instances in which the worked-off metalliferous briquets are smelted in a blast furnace for the production of spiegeleisen a certain amount of fiuxing agents is necessary for slagging off the ash present in the worked-ofl' metalliferous briquets, and when this amount of ash is relatively large an objectionably large amount of fluxing agent is required, with the resultant production of an objectionably large amount of slag. By the practice of our present invention the main bulk, for example, around eighty-five (85) per cent. of the ash of the total carbonaceous material of the charge is in the clinker resulting from the combustion of the bed fuel briquets, and the worked-oft metalliferous briquets are consequently contaminated with only a relatively small amount of ash. On account of this relatively slight ash contamination of the worked-off metalliferous briquets, as well as on account of their physical properties, these briquets are peculiarly well adapted for subsequent treatment in blast furnaces. In addition to retaining their original form, these briquets are moreover of a porous character, due to the removal of the volatilizable metals therefrom, and this porous property of the worked-off briquets is also of advantage in their subsequent treatment.

As a typical instance of the practice of the invention, we will briefly describe a articular charge and the manner of wor ing the same. The charge was made up of the well known Franklin furnace zinc oxid ores and dust coal. Approximately eight -five (85) per cent. of the total coal of the c ar e was briqueted with concentrated waste sul te liquor as the binder, in the manner previously described. The remaining fifteen (15) per cent. of the total coal was mixed with the ore (in the proportion of about ninety (90) parts of ore to ten (10) parts of coal dust) to which was added about three (3) per cent. of concentrated waste sulfite liquor as a binder and the mixture was then briqueted and the briquets baked, as pre- .viously described. The fuel briquets were first charged onto the perforated hearth of the present day customary type of zinc oxid furnace and ignited by the residual heat of the preceding furnacing operation. A thin layer of fuel briquets was first charged, and after these had been well ignited, the remainder of the fuel briquets were charged, producing a layer of bed fuel of about six (6) inches in depth. When this layer of bed fuel had reached full combustion, the briqueted working charge was spread thereon, producing a superposed layer of working charge briquets of about five (5) inches in depth. During these operations, a blast of air was maintained through the perforated grate, and when active reduction of the zinciferous material of the charge began, the efliuent from the furnace was conducted to the oxid drums and thence to the bag-room in the usual manner. The temperature of the charge was maintained at from about 1100 C. to about 1250 C., and the fume emitting period was of substantially four hours duration.

The residual charge consisted of a more or less clinkered coal ash of about three-fourths (i to one and one-half (1%) inches in thickness, resulting from the combustion of the fuel bri nets, and worked-ofi' metalliferous or ore riquets retaining for the greater art their original form with only incipient Fusion. This residual charge was withdrawn from the furnace by hand and the worked-01f ore briquets separated from the remainder of the residual charge for subsequent treatment.

The zinc oxid produced was of a very high grade, free from grit or specks and very bright. The recovery of zinc was remarkably high, being about ninety (90) per cent. on the original zinc content of the raw ore.

While we have hereinbefore specifically described the invention by reference to the production of zinc oxid, including leaded zinc oxid, we wish it to be understood that the invention is applicable to the production of other metal compounds of the volatilizable metals. In particular, we contemplate the production of basic lead sulfate or sublimed lead by the method of the invention. In general, the procedure for the production of sublimed lead is substantially the same as hereinbefore described, substituting, of course, an appropriate plumbiferous material for the zinciferous material. Thus, for example, the bed fuel is briqueted in the manner hereinbeforedescribed, and contains the bulk or greater proportion of the total carbonaceous or other combustible material of the entire charge. The working charge consists of a mixture of finely divided galena or native lead sulfid and carbonaceous material preferably briqueted as hereinbefore described. The workin charge is spread on the ignited layer of fied fuel briquets and upon reaching the reaction temperature. the lead sulfid is reduced and (or) volatilized and subsequently oxidized to lead sulfate and lead oxid thus forming the so-called basic lead sulfate.

The eflluent containing the sublimed lead is withdrawn from the furnace and the metallic product collected in any appropriate manner. The worked-oil plumbiferous briquets containing as they do a relatively small amount of contaminating ash may be advantageously subjected to any appropriate subsequent treatment for the recovery of the non-volatilizable metals of the original metalliferous material. As the source of plumbiferous material, we may use a high grade of native lead sulfid suitably crushed and jigged to free it from accompanying gangue material, or we may use lead sulfid concentrates, such as flotation concentrates, or other appropriate plumbiferous-containing material, with proper additions of sulfur in the form of pyrite, galena, brimstone or other suitable sulfur carrying agents, whenever there is a lack of sulfur in the char to properly sulfate the fume.

The re atively deep layer of bed fuel, when in complete combustion, provides a substantially incandescent sub-stratum of carbonaceous material of appreciable depth upon which rests the metalliferous material of the working charge. By appropriately controlling the amount of combustion supporting gas introduced into the bed fuel, complete utilization of the oxygen of such gas can be effected during its passage through the bed fuel and the superposed metalliferous material can be subjected to a strong and effective reducing atmosphere. This reducing atmosphere may be so controlled as to materially reduce the amount of reducing agent in the Working charge, and in certain instances may even eliminate the necessity of admixing any reducing agent with the metalliferous material of the working charge.

We clailii:

1. In t e production by the Wetherill process of imetal oxids vor other compounds of volatilizable metals, the step of supplying to the furnace hearth a relatively deep layer of bed fuel in the form of briquets, together with the steps of spreading on the ignited layer of bed fuel brlquets a working charge containing metalliferous material and a reducing agent; substantially as described.

2. In the production by the Wetherill process of metal oxids or other compounds of volatilizable metals, the step of supplying to the furnace hearth a relatii'ely deep layer of bed fuel in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containing metalliferous material and a briqueted reducing agent; substantially as described.

3. In the production by the lVetherill. process of metal oxids or other compounds of volatilizable metals, the step of supplying to the furnace hearth a relatively deep layer of bed fuel in the form of briquets, together process of metal oxids or other compounds of volatilizable metals, the step of supplying to the furnace hearth a relatively deep layer of bed fuel in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge composed of a briqueted mixture of metalliferous material and a reducing agent; substantially as described.

5. In the production by the Wetherill process of metal oxids or other compounds of volatilizable metals, the step of supplying to the furnace hearth-a layer of bed fuel containin the greater part of the total combustib e material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containing metalliferous material and a reducing agent; substantially as described.

6. In the production by the Wetherill process of metal oxids or other compounds of volatilizable metals, the step of supplying to the furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containing metalliferous material and a briqueted reducing agent; substantially as described.

7. In the production by the Wetherill process of metal oxids or other compounds of volatilizable metals, the step of su plying to the furnace hearth a la er of be fuel containing the greater part 0 the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containing briqueted metalliferous material and .a reduc ing agent; substantially as described.

8. In the production by the Wetherill of metal oxids or other compounds of volatilizable metals, the step of sugplying to the furnace hearth a layer-of be fuel contain the greater part of the total combustlble material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge composed of a briqueted mixture of metalliferous material and a reducing agent; substantially as described.

9. In the production bythe Wetherill process of metal oxids or other compounds of volatilizable metals, the step of supplyin to the furnace hearth a layer ofbed fue containing from about 75% to about 85% of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containing metalliferous material and a briqueted reducing agent; substantially as described, a

11. In the production by the Wetherill process of metal oxide or other compounds of volatilizable metals, the step of supplying to the furnace hearth a layer of bed fuel containing from about 75% to about 85% of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containin briqueted metalliferous material and a re ucing agent; substantially as described.

12. In the production by the Wetherill process of metal oxids or other compounds of volatilizable metals, the step of su plying to the furnace hearth a layer of bed containing from about 75% to about 85% of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the i ited layer of bed fuel briquets a working 0 arge composed of a briqueted mixture of metalliferous material and a reducing agent; substantially as described.

13. In the production of sublimed lead by the lVethenll process, the step of supplying to the furnace hearth a relatively deep layer of bed fuel in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containing plumbiferous material and a reducing agent; substantially as described.

14. In the roduction of sublimed lead by the Wetherill process, the step of sup lying to the furnace hearth a relatively eep layer of bed fuel in the form of briquets, together with the etc of spreading on the ignited layer of bed fiiel briquets a working charge containing plumbiferous material and a briqueted reducing agent; substantially as described.

15. In the roduction of sublimed lead by the Wetherill process, the step of sup lymg to the furnace hearth a relatively eep fuel layer of bed fuel in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working c arge containin briqueted plumbiferous material and a re ucing agent; substantially as described.

16. In the production of sublimed lead by the Wetherlll process, the step of sup lying to the furnace hearth a relatively d eep layer of bed fuel in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a workin charge composed of a briqueted mixture 0 plum iferous material and a reducing agent; substantially as described.

17. In the production of sublimed lead by the Wetherill process, the step of sup lying to the furnace hearth a la er of bed uel containing the greater part 0 the total combustible material of the'en-tire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containing plumbiferous material and a reducing agent; substantially as described.

18. In the production of sublimed lead by the Wetherill process, the step of supplying to the furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containing lumbiferous material and a briqueted resucing agent; substantiall as described.

19. In the roduction o sublimed lead by the Wetheril process, the step of supplying to the furnace hearth a layer of bed fuel containing the greater part of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge oontainin briqueted plumbiferous material and a re ucing agent; substantially as described.

20. In the production of sublimed lead by the Wetherill process, the step of supplyin to the furnace hearth a layer of bed fue containing the greater art of the total combustible materlal of t e entire charge in the form of briquets, together with the step of s reading on the ignited layer of bed fuel briquets a working char composed of a briqueted mixture of plum iferous material and a reducing agent; substantlally as described.

21. In the roduction of sublimed lead by the Wetheril process, the step of supplym to the furnace hearth a layer of bed fue containing from about 75% to about 85% of the total combustible material of the en-- tire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge charge containing containing plumbiferous material and a reducin agent; substantially as described.

22. n the production of sublimed lead by the Wetherill process, the step of supp ylng to the furnace hearth a layer of bed uel containing from about 75% to about 85% of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ig; nited layer of bed fuel riguets a workin lumbi erous materia and a briqueted re ucing agent; substantially as described.

23. In the roduction of sublimed lead by the Wetheril process, the step of supplyin to the furnace hearth a layer of bed hi5 containing from about 75% to about 85% of .the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containing plumbiferous material and a briqueted reducing agent; substantially as described.

24. In the production of sublimed lead by the Wetherill process, the step of supplying to the furnace hearth a layer of bed fuel containing from about 75% to about 85% of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquetsa working charge composed of a briqueted mixture of plumbiferous material and a reducing agent; substantially as described.

25. In the production of metal oxids or other compounds of volatilizable metals, the step of supplying to the furnace hearth a relatively deep layer of bed fuel in the form of briquets, together with the step of spreading on the ignited layer of be fuel briquets a working charge containing metalliferous material; substantially as described.

26. In the production of metal oxids or other compounds of volatilizable metals, the step of supplying to the furnace hearth a relatively deep layer of bed fuel, together with the step of spreading on the ignited layer of bed fuel a working charge containing briqueted metalliferous material; substantially as described.

27. In the production of metal oxids or other compounds of volatilizable metals, the step of supplying to the furnace hearth a relatively deep layer of bed fuel in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge conta1nmg br1- queted metalliferous material; substantlally as described.

28. In the production of metal oxids or other compounds of volatilizable metals, the step of supplying to the furnace hearth a relatively deep layer of bed fuel, together posed of a briqueted mixture of metalliferous material and a reducing agent; substantially as described.

29. In the production of metal oxide or other compounds of volatilizable metals, the

step of supplying to the furnace hearth a layer of bed fue containing in excess of 25% of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the'ignited layer of bed fuel riquets a working charge containing metalliferous material; substantially as described.

30. In the production of metal oxide or other compounds of volatilizable metals, the step of supslying to the furnace hearth a layer of be fuel containin in excess of 25% of the total combustib e material of the entire charge in the form of briquets, together with the ste of spreading on the ignited layer of bed el brl acts a working c arge containing briquet inetalliferous material; substantially as described.

31. In the productlon of metal oxide or other compounds of volatilizable metals, the step of supplying to the furnace hearth a layer of bed fuel containing from about 75% to about 85% of the total combustible material of the entire charge in the form of briquets, together with the etc of spreading on the ignited layer of bed e1 bri uets a workin charge containing metalhferous materia substantiall as described.

32. In the production of metal oxide or other compounds of volatilizable metals, the step of supplying to the furnace hearth a layer of bed fuel containing from about 75% to about 85% of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel bri nets 0. a Working chargecontaining bri u metalliferous material; substantial y as described.

33. In the reduction of sublimed lead by the Wetherilfprocess, the step of supply to the furnace hearth a relatively deep la er of bed fuel in the form of briquets, toget er with the step of spreading on the ignited layer of bed fuel briquets a working charge containin plumbiferous materal; substantially as escribed.

34. In the production of sublimed lead by the Wetherill process, the step of supplying to the furnace hearth a relatively deep layer of bed fuel, together with the etc of spreading on the ignited layer of bed us] a working charge containing briqueted plum'biferone material; substantially as described.

35. In the production of sublimed lead by the Wetherill rocess, the step of supplying to the furnace earth a relatively deep la er of bed fuel in the form of briquets, toget er with the step of spreading on the layer of bed fuel briquets a working c arge containin briqueted plumbiferous material; substantia y as (1 bed.

36. In the production of.suhlimed lead by the Wetherill process, the step of supplying to the furnace hearth a relatively deep layer of bed fuel, together with the etc of spreading on the igmted layer of bed el a working char composed of a briqueted mixture of, p umbiferous material and a reduci agent substantially as described.

7 In the production of sublimedlead by the Wetherill process, the step of en plying to the furnace hearth a layer of bed fhel containing in excess of 25% of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fuel briquets a working charge containing plumbiferous material; substantially as described. y

1138. Inhthel 1productionhof sublimed lead 15y teWeteri rocessiteste osu in to the heart a'lay r of containing in excess of 25% of the total eom bustible material of the entire charge in the form of b 'quets, together spreading on the ignited layer of bed fuel briquets a working charge containing briqueted plumbiferous material; substantially as described.

39. In the roduction of sublimed lead by the Wetherill process, the step of en plyingto the furnace hearth a layer of bed el containing from about 75% to about 85% of the total combustible material of the entire charge in the form of britgluets, together with the etc of spreading on e ignited layer of bed fue briquets aworking charge containing plumbiferous material; substantially as described.

40. In the production of sublimed lead by the Wetherill process, the step-of supplying to the furnace hearth a layer of bed fue containing from about 75% to about 85% of the total combustible material of the entire charge in the form of briquets, together with the step of spreading on the ignited layer of bed fllel briquets a working charge containing briqueted plumbiferous materia substantially as described.

41. In a process for volatilizing and oxidizing metal values involving the blowing of air into a bed containing combustible material and a mixture of the metal-bearing material and a reducing agent under conditions which will leave the worked-off charge as a clinker and which will produce a volatile fume, the step of supplying the combustible material in the form of a relatively deep layer of briquets; substantiall as described.

42. In a process for volatihzing and oxidizing metal values involving the blowing of air into a bed containing combustible mawith the step of terial and a mixture of the metal-bearing material and a combustible reducing agent under conditions which will leave the worked-off charge as a clinker and which will produce a volatile fume, the step of supplying the combustible material in the form of a relatively deep layer of briquets containing the greater part of the total combustible material of the entire charge; substantially as described.

43. In a process for volatilizing and oxidizing metal values involvin the blowing of air into a bed containin t e metal-bean ing material and combustib e material under conditions which will leave the worked-off charge as a clinker and which will produce a volatile fume, the step of supplying at least part of the combustible material in the form of a relatively dee layer of briquets; substantially as descri ed.

44. In a process for producing sublimed lead involving the blowing of air into a bed containing combustible material and a mixture of the metal-bearing material and a combustible reducing agent under conditions which will leave the worked-oil? charge as a clinker and which will produce a volatile fume, the step of supplying the combustible material in the form of a relatively deep layer of briquets containing the greater part of the total combustible material of the entire charge; substantially as described.

45. In a process for producing sublimed lead involving the blowing of air into a bed containing the metal-bearing material and combustible material under conditions which will leave the Worked-ofi' charge as a clinker and which will produce a volatile fume, the step of supplying at least part of the com bustible material in the form of a relatively dee layer of briquets; substantially as des'cri ed.

In testimony whereof We aflix our signatures.

FRANK G. BREYER. ALBERT E. HALL. GEORGE R. WALT Z.

It is hereby certified that in Letters Patent No. 1,322,090, granted November 18, 1919, upon the application of Frank G. Breyer, Albert E. Hall, and George Waltz, of Pelmerton, Pennsylvania, for an improvement in Production of Metal Oxide andother Compounds of Meta. errors appear in the printed specification requiring correction as follows: Page 2, line 30, for the word thus read this; page 6, line 49, claim 8, after the word Wetherill insert the word process; page 7, lines 100, 108, 116, 125, claims 25, 26, 27, 2s, and page 8, lines 6,.16, 2e, 36, claims 29, 30, 31, 32, after the word production insert the words by the Wetter-ill process;

same page, line 48, claim 33, for the word "supply reed supplying; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofice.

Signed and sealed this 30th day of December, A. D., 1919.

M. H. GOULSTON, Acting Commissioner of Patents.

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